In a communications system, data transmission reliability is usually improved by means of channel encoding, to ensure communication quality. Polar code (polar code) is an encoding technology to which increasing attention is paid, where a composite channel is constructed and a feature of an original channel is changed, so that a capacity of the composite channel is more polarized. Because of such a feature, by means of appropriate encoding design, the polar code technology may be suitable to an original channel that is randomly distributed, and good performance may be achieved and a channel capacity may be approached in many different channel implementations. In addition, the polar code technology can greatly reduce complexity of a receiver by means of interference cancellation decoding, facilitating implementation of the receiver.
To improve communication performance, a hybrid automatic repeat request (HARQ) technology may be used. The HARQ is a technology formed toy combining forward error correction coding and automatic repeat request, and can efficiently compensate for bit errors caused by link adaptation, thereby improving a data transmission rate and reducing a data transmission delay.
However, the feature of the polar code technology is different from that of another existing encoding manner. There are apparent differences in transmission quality of input bits and differences in functions of output bits. Therefore, an encoding capability of a polar code cannot be fully used if the existing HARQ technology is used, resulting in poor HARQ performance.